1. Field of the Invention
This invention relates to artificial teeth, particularly, artificial teeth being capable of providing occlusal equilibration and pressure buffering function.
2. Discussion of the Background
Artificial teeth such as a full denture or a partial denture so far have generally comprised hard raw materials, say, resin teeth, hard resin teeth, porcelain teeth, metal teeth, or Levin bladed teeth for the purpose of masticating food, the teeth which are embedded in alveolar the denture base for the purpose of masticating food transmit naturally the resulted biting or masticating pressure directly to the dental plate.
Therefore, if one point of the artificial teeth embedded in the alveolar portion of the dental base is only slightly higher than the other parts, the other parts of the artificial teeth embedded in the alveolar portion of the dental base as well as the client""s natural teeth can not meet properly nor occlude well because the other major parts are recessed, thereby resulting in the occlusal disproportion because of said higher one point; thus the mucous membrane under the dental base is likely hurt.
An occlusal proportion caused by only one point makes not only the occlusal disproportion but also imbalance throughout the oral cavity.
As some time has elapsed after the artificial denture was fitted up in the mouth, the occlusal disproportion is resulted from the recession or attrition of the occlusal surface, and addition of resin to the resin teeth, replacement of the artificial tooth or teeth, or at last replacement with a new artificial denture must be employed for the treatment. This means that an economic loss, by taking some adjustment time for the client to adapt to the new artificial denture, and thus inviting undesirable burdens of not only the client but also the dentist.
Furthermore, the artificial denture already fitted up must be still used or ground by means of dental machinery when it is needed to provide an appropriate cusp angle suitable to the individual client.
Until now clients can not help having their dentist provide the occlusal equilibration, and it is so difficult for a client to tell the doctor his or her delicate mismatched feeling of occlusion that it takes a lot of time for both of them to get finally a good, stable occlusion.
An example of this kind of artificial denture is as described in Japanese Laid Open Patent Publication No. 7-67890/1995 and the like.
The artificial teeth specified in said Japanese Laid Open Patent Publication NO. 7-67890/1995, as shown in FIG. 1 of the Specification of said Publication, the artificial anterior teeth 11, 12, and 13 in the maxillary site having each a triangular plate at the lingual surface and the artificial anterior teeth 1, 2, and 3 in the mandibular site bite off the eaten food at said triangular flat surface. Artificial teeth 4a, 4b, and 4c in place of the lower first premolar, second premolar and the first molar, respectively, are forming a linked molar band en bloc, and all the molar surfaces are flat. The corresponding artificial tooth 14 in the maxillary site is made as en bloc, a special setting is provided on the molar surface of said artificial tooth 14, thereby the food is ground.
The artificial tooth 5 in place of the mandibular second molar does not touch with the surface of the corresponding artificial tooth 15 when the mouth is closed as in the natural state. When a propensity force towards in one direction is imposed on one front side of the full denture A, said artificial tooth 15 and the corresponding artificial tooth 5 make occlusion, whereby the stability of the full denture A is realized. Such the artificial teeth have been already developed.
The weakness of the full denture and partial denture heretofore specified is as follows; when only one point is slightly higher than the other points, the conditions at the whole parts are inappropriate because the whole parts of the artificial denture are formed with hard, solid materials, and the artificial teeth are embedded solidly in the alveolar portion of the denture base.
As for a full denture formed en bloc, if one point of said full denture is only slightly higher, it affects the whole denture, resulting in instability of the whole artificial denture, thus likely leading to the upset of the whole denture or giving pains to the mucous membrane.
Hence, if only one higher part exists, no treatment for the very narrow point can be done, it gives problems not only to the full denture but also to the whole oral cavity, and prevents the artificial teeth from providing good occlusion.
If no good occlusion is obtained because the occlusal surface is too much recessed at the time of fitting up of a newly prepared artificial denture, or worn out when some time elapsed after the fitting up of the newly prepared artificial denture, a certain amount of resin is added to the artificial teeth for the compensation, or even it must be replaced with a new artificial denture. It is very difficult to keep the best state of occlusion because it is impossible to adjust the occlusal surface portion with a fine tuning for delicate occlusal adjustment corresponding to very slight changes of occlusion and to keep good occlusal equilibration.
When adjusting the cusp angle is individually necessary because of the differences among individual persons, the states of the counterpart teeth, missing teeth, and/or jaws, grinding by means of the dental machinery or addition of the resin or even replacement with newly prepared teeth becomes necessary.
Furthermore, occlusal adjustment of the artificial denture already fitted up can not be performed by the clients themselves, nor can the clients help having their dentist do so.
The artificial teeth specified in the Japanese Laid Open Patent Publication No. 7-67890/1995 should be applied for the full denture, but not for the partial denture at the time said full denture is prepared, and the maxillary and mandibular teeth must be made at the same time. The teeth at one side of the jaw, however, will not function properly, and let alone, only one tooth can not work properly in such the treatment. The artificial teeth have not characteristic properties of the natural teeth, so that they invite problems for most women who love esthetic looking at all times. And occlusal adjustment can not be done by the clients themselves, nor can they help having their doctor do so.
The first object of this invention is to prevent the artificial teeth of the partial denture and full denture from their premature contacts.
The second object of this invention is to prevent any premature contacts of the artificial teeth, and to provide artificial teeth capable of relieving biting and masticating pressure.
The third object of this invention is to prevent the premature contacts, and to provide artificial teeth capable of relieving biting and masticating pressure, and in addition being capable of adjusting freely the position of the occlusal surface, thus resulting in stability of the occlusion.
The fourth object of this invention is to provide artificial teeth whose occlusal cusp angle being easily adjusted for the very client who requires said artificial teeth or denture.
The fifth object of this invention is to provide artificial teeth being easily adjusted as they should be, and also to provide good occlusion without grinding off the occlusal surface of the artificial teeth or adding any resin to said teeth.
The sixth object of this invention is to provide proper occlusion of the artificial teeth being adjusted easily not only by the doctor but also by any client himself or herself.
To achieve the above and other objects, the present invention includes a structure so designed that pressure-buffering layer, which is provided between the occlusal surface portion that received biting pressure and/or masticating pressure and the bonded part that connected to the alveolar portion of the denture base, is made of flexible material capable of buffering any pressure resulted from occlusal force or biting-pressure, and transmitting the reduced pressure to the denture base for the purpose of achieving the first object of this invention stated beforehand.
If one of the teeth happens to make a premature contact and an excessive occlusal force is imposed onto the occlusal surface, the stress breaking layer made of flexible pressure-buffering material becomes elastic and deformed, and this makes it possible for the occlusal surface to recess, moving downwards, thus making the occlusal surface be stopped at the desirable equilibration so that the remaining teeth are totally in the uniform occlusion.
In order to achieve the second object stated beforehand, a shock absorbing system made of flexible buffering material, which is a kind of spring-action element, is provided in said pressure-buffering layer, thus a functional mechanism, which is capable of adjusting the intensity of the stress breaking action, is provided in said shock absorbing system.
In order to achieve the third object stated beforehand, a shock absorbing system made of flexible buffering material, which acts as a kind of spring, is provided in said stress breaking layer and a functional mechanism, which is capable of adjusting the intensity of the stress breaking action, is provided in said shock absorbing system. In addition, an adjusting mechanism provided in the shock absorbing system that is capable of moving freely, including vertical, horizontal, and/or oblique movement, thus capable of making the occlusal surface be moved freely and controlled properly.
In order to achieve the fourth object of this invention stated beforehand, the cusp angle of the occlusal surface is made adjustable.
In order to achieve the fifth object of this invention stated beforehand, the cusp angle of the occlusal surface is made adjustable, and a mechanism that is vertically movable upwards and downwards is provided between said occlusal surface and the connected part. As for said vertically movable mechanism, there are two mechanisms, one mechanism is capable of moving the occlusal surface up-and-down by means of a screw jack, and the other mechanism is capable of moving freely the position of the occlusal surface vertically, horizontally, and/or obliquely.
Furthermore, in order to achieve said fifth object, artificial teeth having a stress breaking layer and said adjusting mechanism can be manufactured in this invention.
In order to achieve the sixth object in this invention stated beforehand, any client is also allowed to be able to adjust the artificial teeth in this invention by himself or herself for the purpose of achieving the second, third, fourth, and fifth objects in this invention as stated beforehand.
The stress breaking layer comprising pressure-buffering material made of elastic raw material, capable of elongating and shrinking freely to some extent, has the function of both properties such as the mass element and spring element. Therefore, the pressure buffering material made of the elastic raw material, capable of elongating and shrinking freely in this invention, has an elastic property as a mass element and a spring property that acts as the spring element.
The elastic material in this invention means non-metallic springs made of composite materials, rubber and rubber analogs, and/or synthetic high-polymers capable of accumulating energy by changing the volume of their bodies. Urethane, silicon, and elastomer plastics are naturally included in this kind of material.
The spring in this invention means a mechanical element capable of accumulating energy by changing their geometry such as the length.
Belleville springs, coil springs, shock absorbers, pneumatic springs, flat springs, torsion bars, bar springs, volute springs, and shape memory alloys, are included in this category of said springs in this invention.
As for the springs, there are three cases; one of them in which individual springs are used independently according to the intensity of the occlusal pressure, the second case in which a spring system capable of adjusting the stress of the springs from the outside force according to the intensity of the occlusal pressure by means of setting-up springs inside the main springs, and the third case in which the springs provided in the main spring, capable of adjusting their strength of spring action, and also moving their position i.e. capable of moving freely, including vertical, horizontal, and/or oblique movement, according to the intensity of the occlusal pressure as adjusted by an outside force.
Hence, for the stress breaking layer made of flexible material, capable of elongating and shrinking freely to some extent, any forms or any materials are suitable as long as said forms and/or materials suitable to the functions stated beforehand, and the system can be made of only elastic materials, and any combinations of any elastic materials and springs can be employed in this invention.
As for said springs in this invention, their reactionary stress to meet the intensity of the occlusal pressure, is adjustable from the outside of the dental corona.
In addition, in this invention a flexible pressure buffering material is provided at the proximal surface so that it allows the occlusal surface to recess freely to some extent, although the undesirable frictional force caused by said proximal teeth does sometimes prevent to do so, when the occlusal surface of the artificial teeth should recess vertically by the occlusal pressure and/or masticating pressure.
As for the proximal surface, some composite materials, rubber and/or rubber analogs, or synthetic resins as the mass element are provided for this purpose, or the occlusal surface that should recess are formed to avoid the surface portion of the proximal teeth.
Artificial teeth for artificial denture with an adjusting mechanism that are capable of allowing the occlusal surface to move freely, including vertical, horizontal, and oblique movements between the occlusal surface and connecting portion, can also be manufactured.
Furthermore, artificial teeth can be so fabricated that they have a combination of the stress breaking layer and the adjusting mechanism.
Artificial teeth whose adjusting mechanism capable of moving freely, including vertical,horizontal, and/or oblique movement, and artificial teeth whose adjusting mechanism is capable of only vertical movement, or only horizontal movement, or only oblique movement are also available, and the artificial teeth whose mechanism is capable of only two kinds of movements out of the vertical, horizontal, and oblique movements are available, too.
As for the mechanism for adjusting the vertical movement of the occlusal surface, any of the following can be applied; screw jack, link-work up-and-down mechanism, cam-work, gear-work and the like that are capable of fine-adjusting, keeping the once-adjusted status intact, and not changing said status by any factors other than the renewal procedure of the adjusting.
The cusp angle is allowed to be changed freely so that the cusp angle of the occlusal surface is adjustable in order to stabilize the occlusion. It is desirable to employ a method to change the angle of the cusp portion by means of the screw jack by letting the central groove of the occlusal surface be the pivotal point.
As for the adjustment of the cusp angle, there are such cases; the case in which the individual cusp is adjustable with regard to the molar teeth, the case in which the cusp angles at either side of the bucca, and the cusp angle including the two cusp angles at either side of the lingua are adjustable independently, and the case in which when the cusp angle of the premolar and/or molar teeth at both sides of the bucca is adjusted, the cusp angle of the cusp at the lingua is adjusted by the same angle as said adjustment at the buccal sides in relation with each other.
Denture manufacturing need not be so much modified for practicing the artificial teeth and dentures as stated in this invention, but will enable the dentists and clients themselves to set up the artificial teeth or dentures in their mouth and to adjust the occlusion by themselves, thus the problems involved in the preparing and wearing the conventional artificial teeth and dentures will be solved by this invention.